The present invention relates to a specialized catheter and a method of placing the catheter and stents in a bifurcated vessel. More particularly, the method includes placing a primary stent in a primary vessel and a secondary stent in at least one secondary vessel which branches from the primary vessel, the secondary branch vessel(s) and the primary vessel forming at least one bifurcated vessel. The catheter is specialized to allow passage of a guidewire through the wall of the catheter and remove the primary stent assembly so that the secondary stent may be placed into position in the secondary vessel.
A stent, sometimes referred to as a graft, is an endoprosthetic device that is placed within or implanted in a tubular vessel, such as a vascular vessel like an artery or vein, or other vessel, such as intestine, esophagus or other tubular body organ in animals, and particularly humans, for treating blockages, stenoses or aneurysms of the vessel. The stent is implanted within the vessels to act as an internal scaffold or reinforcement to support collapsing, previously fully or partially occluded, weakened or abnormally dilated portions of the vessel wall. Typically, stents have been used to treat dissections in blood vessel walls, for example following balloon angioplasty of the coronary arteries and peripheral arteries, and to improve results of angioplasty by reinforcing the vessel wall. Stents also have been implanted in other body vessels, such as the gastrointestinal tract, particularly the urinary tract, the bile duct, the esophagus and the tracheo-bronchial tree to support weakened or otherwise damaged walls of those organs.
Typically, stents are elongated tubular products that have a first, unexpanded condition in which they are threaded through the appropriate body organs, such as blood vessels, by use of catheters and guidewires. Some stents are expanded by way of the use of a small balloon which is expandable by a fluid, such as a sterile saline solution, when the stent reaches the desired location. There are great number of examples of stents having various types of geometry, such as those disclosed in U.S. Pat. No. 4,739,762 of Palmaz (commercialized in various forms as the Palmaz stent), U.S. Pat. No. 5,895,406 of Gray et al. and U.S. Pat. No. 5,922,021 of Jang. Other types of stents have been developed that are made of materials, such as an alloy of nickel and titanium called nitinol, which, when initially compressed, are within the sheath of a catheter, are in an unexpanded state, but when released from the catheter sheath, self-expand to an appropriate degree without the use of a balloon to bear against the vessel walls and retain them in an open condition. A couple of examples of stents of this type are shown in U.S. Pat. No. 6,923,829 of Boyle et aL and U.S. Pat. No. 6,936,066 of Palmaz et al. Stents have been commercialized by Cordis Corp. (a Johnson & Johnson Company), Guidant Corp., Boston Scientific Corp., Medtronic Inc., all of the United States, and Medinol, Ltd. of Israel, among others. The manufacture and installation of stents is a multi-billion dollar business which is increasing annually, particularly as populations age.
Some stents are drug-eluting stents by virtue of the material from which the stents are made having properties particularly relating to antithrombotic activity, or antirestenosis activity. Often during procedures relating to vessel repair or even the insertion of the stents, blood may form clots, resulting in potentially serious or fatal thromboses and, over time, scar tissue or other matter builds up in the vessels, often in the vicinity of and on, and even as a result of, the use of a stent, resulting in re-blockage or restenosis of the vessel. Drug-eluting stents, which may also include coatings, thin reservoirs containing leachable active ingredients, and other techniques, have been developed and are in use to help prevent or treat such thromboses or restenosis. Among a great many examples are drug-eluting stents of a type disclosed in U.S. Pat. No. 6,120,536 of Ding et al., or U.S. Pat. No. 7,037,332 of Kutryk et al., which discloses a device coated with an antibiotic that promotes adherence of endothelial cells to the device. Certain materials used in making stents are themselves antirestentotic or antithrombogenic, such as U.S. Pat. No. 6,379,383 of Palmaz et al.
The use of stents in relatively straight and unbranched vessels is fairly straightforward. Complications arise when the damage to be repaired is near or at ajunction or point of bifurcation in bifurcated vessels where a branch vessel joins a main vessel. There are difficulties in inserting stents both in the main or primary vessel and in the branched or secondary vessel, which may result in further damage to the vessel with increased risk of thrombosis and embolism or even additional perforation of the vessel. Complications that may arise are disclosed in U.S. Pat. No. 6,962,202 of Vardi et al., which discloses one type of apparatus and a method of using it for treating bifurcated vessels. Other examples of stents and methods of inserting them for use in bifurcated vessels are disclosed in U.S. Pat. No. 6,440,165 of Richter et al. and in U.S. Patent Application Publication No. US 2004/0186560, published Sep. 23, 2004. The disclosures of these and all other patents and publications mentioned herein are hereby incorporated herein by reference. Each of the patents or publication mentioned in this paragraph discloses alternative arrangements and methods of insertion. Despite the various techniques, there are still certain inefficiencies and concerns with the methods of inserting stent assemblies in bifurcated vessels. The present invention overcomes the difficulties in alignment and insertion of various types of stents.
The present invention provides a specialized primary stent catheter and the method of its use to positively and efficiently align and insert a stent assembly comprising a primary stent and a secondary stent into a bifurcated vessel. The stent may be a balloon-expandable stent or a self-expandable stent and may include a coating or be made of materials by which it may also be a drug-eluting stent. The stent is made of materials or includes imageable coatings or other markings to allow ready determination of its location within and passage through a vessel, which is particularly important when dealing with bifurcated vessels. Such coatings and technologies are well known to those skilled in the art. Substantially any type or configuration of stent may be used with the method of the present invention.
A portion of the primary catheter is separable so that after a primary guidewire guides the primary stent into a primary vessel, a secondary guidewire may be removed from the lumen of the primary catheter and guide a secondary stent into a secondary vessel. The separable portion of the catheter does not significantly protrude from a cross-section of the catheter, thus making the surface of the catheter less obtrusive as it travels through a vessel than would an external guide mounted on the body of the catheter.
The present invention provides for an improved catheter to guide the stent assembly into a bifurcated vessel, along with the method for placing the stent assembly into the bifurcated vessel, with complete stent support for the full bifurcated vessel, which reduces the risk of restenosis or other adverse consequences associated with treating bifurcated vessels.